Phonograph record and method of playing same



Aug. 14, 1934. H LOUGHRIDGE 1,?69,895

PHONOGRAPH RECORD AND METHOD OF PLAYING SAME Filed Nov. 10, 1930 2 Sheets-Sheet l 1?; j l INVENTOR. r4 /5 1934. M. H. LOUGHRIDGE 1,969,395

PHONOGRAPH RECORD AND METHOD OF PLAYING SAME Filed Nov. 10,- 1930 2 Sheets-Sheet '2 M N VEN TOR.

Patented Aug. 14, 1934 PHONOGRAPH RECORD AND METHOD OF.

PLAYING SAME Matthew H. Loughridge, Bogota, N. J.

Application November 10, 1930, Serial No. 494,631

10 Claims.

This invention relates to phonograph records and to the method of recording and playing the same and has for an object to prevent the unauthorized use or" phonograph records and to introduce a certain degree of secrecy in transmitting and using the subject matter recorded on the record. Another object of the invention is to enable phonograph records to be recorded on standard machines with a particular characteristic that prevents their reproduction on standard machines; another object or" the invention is to record records according to a code key and which are reproduceable only by a corresponding code key; another object of the invention is to provide records of sheet stock which are grooved to increase their rigidity; other objects of the invention will appear from the following specification and the accompanying drawings, in which,

Fig. l is a plan view or" a turntable with a record and an attachment ior recording orplaying the record according to this invention;

Fig. 2 is a side elevation corresponding to Fig. l with the record and attaching device in. n 7 V the stern there is considerable difiiculty in finding I section; V

Fig. 3 is a transverse section of the record shown in Fig. 1 in the reverse position;

Figs. 4, 5, 6, and 7. are details, partly sectioned, showing the relation of the record to the stem 300i the turntable;

Fig. 8 is a plan view, partly sectioned, showing the attaching device for positioning the record in the turntable stem;

Fig. 9 is a detail of the base part of the attaching device with the stem sectioned;

' Fig. 10 is a side elevation of one form of the attachingdevice complete;

Fig. 11 is a view from the bottom of a modified form of attaching device;

40 In the ordinary construction of phonographs,

it is the intention that records shall be inter-1 changeable so that they may be played ondifferent machines. This is desirable for musical and ordinary commercial records, butit is not desirable in records that are used for dictaphoneand similar purposes. In fact, the value of such records in many cases would be considerably enhanced if they were so constructed. that they could not be playedon the ordinary phonograph. It is desirable, however, to embody in, or provide attachments. to, the standard type" when it is placed: on a turntable and. the central of. phonograph that will enable these machines to be used for making dictaphone records orfor reproducing such: records, without, however impairing their intended. use in the; playing off.

that used in recording thespiral.

standard records. The purpose of the present invention is to provide an attachment to phonographs of the standard type which puts a char acteristic into the record relative to the sound grooves when it is being recorded which praci,

tically prevents this record being reproduced onany machine except those provided with a corresponding attachment. By restricting the use. of these attachments it is possible to make the subject of a record practically a secret from un- [a authorized persons.

In making a record according to standard practice the record blank is centered through a central aperture on the stem of the turntabl'eand" the spiral is inscribed on the record by a feeding mechanism carrying the stylus over the record. When the record is to be reproduced it is cen tered in a similar manner on the stem of the turntable and the stylus is fed by following the grooves oi the record in a free tone arm type of mechanism, or by a feeding mechanism similar to If the aperture in the record fitting over the stem of the turntable .ismaterially larger than or in positioning the record so that the spiral is concentric with the stem of the turntable and with the centre of rotation. If the spiral isnot properly centered the stylus is subject to a trans-. verse movement equal to the degree of'eccentricity which efiects the results obtained from the record, and, when an eccentrically mounted record is running there is considerable difiiculty in placing the stylus of thepick-up head in the first groove of the record. 9a

In. the present invention the record is purposely off-centered from the stem of the turntable when it is being inscribed with the result that it can only be reproduced when correspondingly centered on. the turntable of areproducing machine. In 9 practice this is obtained by providing in the centre of the record blank a comparatively large circular opening. In this opening an adapter is placed which is a comparatively: close fit and which is provided with an aperturetoreceiVethe 100.,

tiveto the opening in the record and it isapparent that a record so made can be reproduced-only" opening is correspondingly off-centered relative; to the stem of the turntable; This gives'thecen-i tral aperture of the recorda. characteristic rel'ae 110.?

tive to the sound grooves when the record is inscribed which must be matched when the record is reproduced.

Ihe adapter, called an eccentric, which fits the aperture of the record is provided with latching means whereby the record may be secured to this eccentric in a particular position and thereby the degree of eccentricity of the sound grooves is determined, making it necessary to establish the same degree of eccentricity in the record when it is being played and thus a variety of combinations may be obtained in which records may be selectively used and may be efiectively prevented from otherwise being used. v

This invention is intended to be practiced with standard phonograph mechanisms which are ordinarily used with standard records and for this purpose the adapter is provided which is applied by a spring clutch to the stem of the turntable and is readily replaceable. The adapter may be formed to take specific sizes of records or it may be made adjustable to take difierent sizes of records and, in this way, by controlling the use of the adapter, the use of the records is controlled.

In the drawings, 11 is the turntable mounted on the stem 16 of the phonograph mechanism 1'7. 12 is the record or record blank with the sound grooves 13 and provided with an annular ridge at 14 and another annular ridge at 15 leaving a suriface between these ridges for the spiral of the The'adapter 23 is provided with a stem enclosing the turntable stem 16 and securing the top flange 21 in place. This flange engages the coil spring 29 bearing upon the washer 28 which engages the ring 25, mounted on the eccentric 23.

' 3A plunger 26 depends from the ring 25 and enters an aperture in the base 22 to engage an aperture in the record as indicated at 26 so that the record and'adapter are locked together in this position and rotated by the turntable. The plunger 26 "may be released from the record by means of a latch 27.

The degree of eccentricity between the aperture of the record and the turntable stem will be understood from Figs. 4, 5, 6, and '7 in which line b passes through the centre of the aperture while line a passes through the centre of the stem and the degree of eccentricity is represented by the distance between lines a and b. The tab 32 indicates one position of the record on the eccentric 60223 in Fig. 4 and the tab 32 which looks the record 14 to the eccentric 23 in Fig. 5, indicates another position of the record with a 'difierent degree of eccentricity relative to the stem of the turntable. It is apparent that a record locked to the eccen- 5 itric 23 in the position shown in Fig. i would not be properly centered if applied to another eccentric locked to the record in the position shown in Fig. 5, hence a selective effect is secured in the use of the adapters which further increases the 'ielement of secrecy in the application of the invention. In Figs. 6 and '7 an additional tab is indicated at 3211 on the eccentric 23 for the purpose of making the adapters specific to the use of a particular type of record having apertures registering with these tabs.

The adapter may be constructed of a solid piece of metal having a spring engagement with the turntable stem, an eccentric suitably arranged thereon to engage the record aperture and with tabs corresponding to 32 arranged as desired. In Figs. 2 and 10 the adapter is made adjustable so that it can be used to make records having different locking positions on the eccentric and to correspondingly reproduce such records. This comprises the base 22 having formed integral therewith the eccentric 23 and the hollow split stem 31. The collar or ring 25 is mounted on the eccentric 23 and rotates on top of base 22 about this eccentric. The base 22 is provided with apertures as indicated at 33, 34, 35, and 36 and the collar 25 is provided with one or more depending stems 26 which register with the apertures in 22 and engage the record in the position desired relative to the centre of stem 31. Fig. 11 indicates a modified form of this device in which the eccentrio is increased in diameter at 23aand two looking members 37 and 38 are arranged to engage the record.

The record as indicated in Fig. 2 is preferably made from sheet stock such as aluminum or celluloid and is provided with annular ridges at 14 and 15 between which the sound grooves are placed. These ridges stiffen the stock and prevent buckling. It will be observed in Fig. 2 that the surface of the record slopes downwardly toward the outer edge and when reversed, as in Fig. 3, the surface slopes in the opposite direction. In addition to stiffening the stock of the recordsthe ridges help to reduce the adhesion between the turntable and the record which ordinarily obtains on a felt covered turntable with the result that if the record is placed on the turntable without some securing means it will slip in operation and will automatically become decentered. I

In considering the operation of this invention the usual pick-up head, preferably of the magnetic type, is used to control the stylus which is mounted on an arm substantially tangent to the movement of the sound grooves. The record blank is mounted on the eccentric of the adapter and thesound grooves are thus inscribed eccentric to the aperture in the record through which the turntable stem projects although these sound grooves are concentric with the stern of the turntable in this position.

When the record is removed and applied to another turntable there is not only the difficulty of finding a centre in the comparatively large opening through which the turntable stem projects, but the playing centre of the sound grooves is displaced from the centre of this opening to anextent that may be varied as Welland hence this centre cannot be found except by a great deal of experimentation. However, when the record is mounted on an adapter having the same degree of eccentricity as the adapter on which it was originally made, the playing centre is thereby established.

If an attempt is made to reproduce these records with the sound grooves out of centre, this will cause a transverse movement of the stylus relative to the turntable which makes the stylus point follow a line which experiments indicate to be an ellipse. If the record is played at a comparatively high speedthis ellipse, by the centrifugal force, such force, for instance, as throws a loose object from a rotating turntable at a tangent, will throw the stylus off the sound grooves and this action is somewhat facilitated by the downwardly sloping surface of the record towards the outer edge as indicated in Fig. 2. On the other hand, if the record is played at a slow speed it is possible that in records of the ordinary type the stylus head will hold the sound grooves but the articulation is very much impaired. For secrecy in reproduction, high speed recording is to be preferred as far as the application of this invention at the present is known.

t is apparent that if an attempt is made to reproduce records which are de-centered on a machine having a screw fed mechanism, that it is impossible for this mechanism to carry the stylus over the sound grooves moving in an eccentric and keep the stylus tracking in the groove.

Having thus described my invention, I claim;

1. A phonograph record of the disc type having a circular aperture for mounting on the stem of a turntable, but of substantially greater diameter than the stem of said turntable and sound grooves on said record eccentric to said record disc and having their cen re within said aperture.

2. A phonograph record of the disc type having a circular aperture for mounting on the stem of a turntable but substantially larger than said stem and sound grooves on said record eccentric to said record disc but having their centre within said aperture.

3. The combination of a phonograph turntable having a stem with a device engaging said stem for clamping a record on said turntable, said device having a portion eccentric to said stem engaging an aperture in the record which aperture is eccentric to the sound grooves of the record.

4. The combination of a phonograph turntable having a stem, a device engaging said stem for positioning a record having an aperture larger than stem on said turntable, said device having a locking engagement with said record to centre the sound grooves of the record about the turntable stem.

5. The combination of a phonograph turntable having a stem, with a device engaging said stem for selectively positioning a record on said turntable having an aperture larger than said stem.

6. The combination of a phonograph turntable having a stem with a device engaging said stem for positioning a record having an aperture larger than said stem on said turntable and means embodied in said device for adjustably engaging the record.

7. The combination of a phonograph turntable having a stem with a device engaging said stem for positioning a record on the turntable having an aperture eccentric to the sound grooves of the record, said device having a portion eccentric to said stem for engaging the record.

8. A phonograph record comprising a record blank with sound grooves having a central aperture therein for placing on the stem of a phonograph turntable, the aperture being substantially larger than the stem, said sound grooves being located eccentric to said aperture and having their centre within said aperture and means for centering said sound grooves on said stem.

9. A phonograph record comprising a disc of sheet stock with annular grooves on the active surface thereof and a circular aperture for mounting on the stem of a turntable and substantially larger than the stem of the turntable, said aperture being eccentric to the sound grooves of the record and means for centering the sound grooves on said stem.

10. A phonograph record comprising a disc of sheet stock having a central circular aperture for the stem of a turntable and substantially larger than the stem of the turntable, an annular surface on said record for receiving sound grooves, said surface being inclined relative to the face of the turntable and said sound grooves being eccentric relative to the central aperture of the turntable and having their centre located within said aperture.

MATTHEW H. LOUGHRIDGE. 

